Method for preparing carbon microspheres through supercritical water resource degradation of waste plastics

Abstract

The invention discloses a method for preparing carbon microspheres by waste plastic supercritical water resource degradation, and belongs to the technical field of carbon microsphere preparation, and the method comprises the following steps: S1, weighing a plastic sample and ultrapure water, and filling the weighed plastic sample and ultrapure water into a quartz tube reactor; s2, argon is introduced to exhaust air; s3, sealing the open end of the quartz tube reactor; s4, heating is conducted; s5, cooling is carried out, and at the moment, solid residues, namely the carbon microspheres, exist in the quartz tube reactor; according to the method, resource recycling of the waste plastics can be achieved, the prepared products are uniform in particle size and high in value, meanwhile, the final products are hydrogen, methane, carbon monoxide, carbon dioxide and some small-molecule clean products, carbon emission is reduced, and energy conservation and environmental protection are achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of carbon microsphere preparation, and specifically relates to a method for preparing carbon microspheres by supercritical water resource degradation of waste plastics. Background Art

[0002] Carbon materials refer to non-metallic materials obtained through a series of processing using organic substances such as coal, petroleum or their processed products as the main raw materials.

[0003] Carbon microspheres are a type of carbon material. They are widely used in many fields because of their high specific surface area and high stacking density, as well as good electrical conductivity, thermal conductivity, self-sintering and chemical stability.

[0004] At present, the methods for preparing carbon microspheres generally include chemical vapor deposition, solvent thermal method, template method, mechanical ball milling method and emulsification method. Among them, the chemical vapor deposition method has high requirements on temperature, resulting in high energy consumption. Due to the limitations of process conditions, the output is relatively low, and the functional groups on the surface of the obtained product are relatively few, which may affect its application performance; the scope of application of the solvent thermal method is relatively limited; the template removal process of the template method is relatively cumbersome and complicated, and the structure and properties of the carbon microspheres may be destroyed during the removal process. At the same time, the quality and performance of the final product of the preparation process are affected by many factors including the selection of the template and the reaction conditions; due to the influence of high-frequency collisions, the carbon microspheres prepared by the mechanical ball milling method have poor sphericity and poor particle size uniformity; the emulsification method has high requirements on raw materials, requires soluble mesophase asphalt as raw material, and requires high-temperature thermally stable medium and surfactant, the process flow is complicated, the prepared mesophase carbon microspheres can be melted, and need to be infusible before application, which increases the complexity of the process flow, requires more equipment, large investment, and high operating costs.

[0005] That is, the current preparation methods of carbon microspheres have problems such as complex process, large investment, high energy consumption, high cost, uneven product quality and environmental issues.

[0006] In view of this, a method for preparing carbon microspheres by supercritical water resource degradation of waste plastics was designed to solve the above problems. Summary of the invention

[0007] In order to solve the problems raised in the above background technology, the present invention provides a method for preparing carbon microspheres by supercritical water degradation of waste plastics, which has the characteristics of high resource recovery and utilization efficiency, high product value, energy saving and environmental protection.

[0008] To achieve the above object, the present invention provides the following technical solution: a method for preparing carbon microspheres by supercritical water resource degradation of waste plastics, comprising the following steps:

[0009] S1: Weigh the plastic sample and ultrapure water using a precision balance and load them into a quartz tube reactor;

[0010] S2: introducing argon gas into the quartz tube reactor to exhaust the air in the quartz tube reactor so that there is no oxygen in the quartz tube reactor;

[0011] S3: sealing the open end of the quartz tube reactor by an oxyhydrogen flame generated by an oxyhydrogen flame sealing machine;

[0012] S4: placing the sealed quartz tube reactor into a heating furnace for heating;

[0013] S5: The heated quartz tube reactor is removed from the heating furnace and cooled. At this time, there are solid residues, namely carbon microspheres, in the quartz tube reactor.

[0014] Furthermore, in step S1, the plastic sample includes polystyrene, acrylonitrile-butadiene-styrene terpolymer, polycarbonate and polypropylene.

[0015] Furthermore, in step S1, the plastic sample needs to be cleaned and dried before being loaded into the quartz tube reactor.

[0016] Furthermore, in step S1, the resistivity of ultrapure water is greater than 18.25 MΩ.cm.

[0017] Furthermore, in step S2, the ventilation rate of argon gas is 100 ml / min, and the ventilation time is 5 min.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] The present invention prepares carbon microspheres by degrading waste plastics through supercritical water gasification. The method can not only realize the resource recycling of waste plastics, but also the prepared products have uniform particle size and high product value. At the same time, the final products are hydrogen, methane, carbon monoxide, carbon dioxide and some small molecule clean products, which reduces carbon emissions and saves energy and is environmentally friendly. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 The flowchart of the method of the present invention is shown in Figure 1, wherein 1 represents a quartz tube reactor, 2 represents ultrapure water, 3 represents a plastic sample, 4 represents an oxyhydrogen flame sealing machine, 5 represents a heating furnace, 6 represents a thermocouple, and 7 represents a solid product attached to the surface of the reactor tube wall after the reaction;

[0021] Figure 2 This is an electron microscope image of carbon microspheres prepared using polystyrene as a plastic sample in the present invention;

[0022] Figure 3 The particle size distribution diagram of carbon microspheres prepared by using polystyrene as a plastic sample in the present invention;

[0023] Figure 4The electron microscope image of the carbon microspheres prepared by using acrylonitrile-butadiene-styrene terpolymer as the plastic sample of the present invention;

[0024] Figure 5 The particle size distribution diagram of carbon microspheres prepared by using acrylonitrile-butadiene-styrene terpolymer as a plastic sample of the present invention;

[0025] Figure 6 This is an electron microscope image of carbon microspheres prepared using polycarbonate as a plastic sample of the present invention;

[0026] Figure 7 The particle size distribution diagram of carbon microspheres prepared by using polycarbonate as a plastic sample of the present invention;

[0027] Figure 8 This is an electron microscope image of carbon microspheres prepared using polypropylene as a plastic sample in the present invention;

[0028] Fig. 9 The particle size distribution diagram of carbon microspheres prepared by using polypropylene as a plastic sample in the present invention;

[0029] Fig.10 The electron microscope images of carbon microspheres prepared by using high-impact polystyrene as plastic sample at different reaction times in the present invention;

[0030] Fig.11 This is a graph showing the average particle size of carbon microspheres prepared at different reaction times using high impact polystyrene as a plastic sample of the present invention;

[0031] Fig.12 The electron microscope images of carbon microspheres prepared at different reaction temperatures using high impact polystyrene as a plastic sample of the present invention;

[0032] Fig.13 This is a graph showing the average particle size of carbon microspheres prepared at different reaction temperatures using high impact polystyrene as a plastic sample. DETAILED DESCRIPTION

[0033] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0034] Embodiment 1

[0035] A method for preparing carbon microspheres by supercritical water resource degradation of waste plastics, comprising the following steps:

[0036] S1: 8.20 mg of cleaned and dried polystyrene and 73.78 μl of ultrapure water with a resistivity greater than 18.25 MΩ.cm were weighed by a precision balance and loaded into a quartz tube reactor;

[0037] S2: introducing argon gas into the quartz tube reactor and exhausting the air in the quartz tube reactor to make the quartz tube reactor oxygen-free, wherein the ventilation rate of argon gas is 100 ml / min and the ventilation time is 5 min;

[0038] S3: sealing the open end of the quartz tube reactor by an oxyhydrogen flame generated by an oxyhydrogen flame sealing machine;

[0039] S4: placing the sealed quartz tube reactor into a heating furnace for heating at a temperature of 700°C, a reaction pressure of 23 MPa, and a heating time of 10 min;

[0040] As the temperature in the heating furnace rises, the ultrapure water expands due to heat, generating autogenous pressure and forming a supercritical water reaction environment. In the initial stage of gasification degradation, the waste plastic first undergoes a melting process and then effectively disperses in the supercritical water environment. As the chemical reaction continues to advance, the waste plastic gradually depolymerizes to form a large number of plastic monomers. These monomers continue to undergo a series of complex reactions such as cracking, reforming and polycondensation in supercritical water. When the concentration of waste plastic-based aromatic hydrocarbon fragments in the water accumulates to a certain critical value, it will trigger a chemical reaction of polycondensation nucleation to form a primary structure of microspheres, and in the subsequent mature carbonization process, a novel carbon microsphere material will be formed.

[0041] S5: The heated quartz tube reactor is removed from the heating furnace and cooled. At this time, there are solid residues, namely carbon microspheres, in the quartz tube reactor.

[0042] The solid residue in the quartz tube reactor was analyzed and the mass of carbon accounted for about 61% of the mass of carbon in the raw material. The electron microscope image is shown in the attached figure. Figure 2 The particle size distribution diagram is shown in the attached Figure 3 As shown, the gas phase product components (including C2H x , CO2, CH4, CO and H2), the particle size average, standard deviation, coefficient of variation and carbon conversion rate of carbon microspheres are shown in the following table:

[0043]

[0044] Embodiment 2

[0045] A method for preparing carbon microspheres by supercritical water resource degradation of waste plastics, comprising the following steps:

[0046] S1: 8.20 mg of washed and dried acrylonitrile-butadiene-styrene terpolymer and 73.78 μl of ultrapure water with a resistivity greater than 18.25 MΩ.cm were weighed by a precision balance and loaded into a quartz tube reactor;

[0047] S2: introducing argon gas into the quartz tube reactor and exhausting the air in the quartz tube reactor to make the quartz tube reactor oxygen-free, wherein the ventilation rate of argon gas is 100 ml / min and the ventilation time is 5 min;

[0048] S3: sealing the open end of the quartz tube reactor by an oxyhydrogen flame generated by an oxyhydrogen flame sealing machine;

[0049] S4: placing the sealed quartz tube reactor into a heating furnace for heating at a temperature of 700°C, a reaction pressure of 23 MPa, and a heating time of 10 min;

[0050] S5: The heated quartz tube reactor is removed from the heating furnace and cooled. At this time, there are solid residues, namely carbon microspheres, in the quartz tube reactor.

[0051] The solid residue in the quartz tube reactor was analyzed and the mass of carbon accounted for about 71% of the mass of carbon in the raw material. The electron microscope image is shown in the attached figure. Figure 4 The particle size distribution diagram is shown in the attached Figure 5 As shown, the gas phase product components (including C2H x , CO2, CH4, CO and H2), the particle size average, standard deviation, coefficient of variation and carbon conversion rate of carbon microspheres are shown in the following table:

[0052]

[0053] Embodiment 3

[0054] A method for preparing carbon microspheres by supercritical water resource degradation of waste plastics, comprising the following steps:

[0055] S1: 8.20 mg of washed and dried polycarbonate and 73.78 μl of ultrapure water with a resistivity greater than 18.25 MΩ.cm are weighed by a precision balance and loaded into a quartz tube reactor;

[0056] S2: introducing argon gas into the quartz tube reactor and exhausting the air in the quartz tube reactor to make the quartz tube reactor oxygen-free, wherein the ventilation rate of argon gas is 100 ml / min and the ventilation time is 5 min;

[0057] S3: sealing the open end of the quartz tube reactor by an oxyhydrogen flame generated by an oxyhydrogen flame sealing machine;

[0058] S4: placing the sealed quartz tube reactor into a heating furnace for heating at a temperature of 700°C, a reaction pressure of 23 MPa, and a heating time of 10 min;

[0059] S5: The heated quartz tube reactor is removed from the heating furnace and cooled. At this time, there are solid residues, namely carbon microspheres, in the quartz tube reactor.

[0060] The solid residue in the quartz tube reactor was analyzed and the mass of carbon accounted for about 62% of the mass of carbon in the raw material. The electron microscope image is shown in the attached figure. Figure 6 The particle size distribution diagram is shown in the attached Figure 7 As shown, the gas phase product components (including C2H x , CO2, CH4, CO and H2), the particle size average, standard deviation, coefficient of variation and carbon conversion rate of carbon microspheres are shown in the following table:

[0061]

[0062] Embodiment 4

[0063] A method for preparing carbon microspheres by supercritical water resource degradation of waste plastics, comprising the following steps:

[0064] S1: 8.20 mg of cleaned and dried polypropylene and 73.78 μl of ultrapure water with a resistivity greater than 18.25 MΩ.cm were weighed by a precision balance and loaded into a quartz tube reactor;

[0065] S2: introducing argon gas into the quartz tube reactor and exhausting the air in the quartz tube reactor to make the quartz tube reactor oxygen-free, wherein the ventilation rate of argon gas is 100 ml / min and the ventilation time is 5 min;

[0066] S3: sealing the open end of the quartz tube reactor by an oxyhydrogen flame generated by an oxyhydrogen flame sealing machine;

[0067] S4: placing the sealed quartz tube reactor into a heating furnace for heating at a temperature of 700°C, a reaction pressure of 23 MPa, and a heating time of 10 min;

[0068] S5: The heated quartz tube reactor is removed from the heating furnace and cooled. At this time, there are solid residues, namely carbon microspheres, in the quartz tube reactor.

[0069] The solid residue in the quartz tube reactor was analyzed and the mass of carbon accounted for about 52% of the mass of carbon in the raw material. The electron microscope image is shown in the attached figure. Figure 8 The particle size distribution diagram is shown in the attached Fig. 9 As shown, the gas phase product components (including C2H x, CO2, CH4, CO and H2), the particle size average, standard deviation, coefficient of variation and carbon conversion rate of carbon microspheres are shown in the following table:

[0070]

[0071] Embodiment 5

[0072] A method for preparing carbon microspheres by supercritical water resource degradation of waste plastics, comprising the following steps:

[0073] S1: 3.88 mg of cleaned and dried high-impact polystyrene and 73.78 μl of ultrapure water with a resistivity greater than 18.25 MΩ.cm were weighed by a precision balance and loaded into a quartz tube reactor;

[0074] S2: introducing argon gas into the quartz tube reactor and exhausting the air in the quartz tube reactor to make the quartz tube reactor oxygen-free, wherein the ventilation rate of argon gas is 100 ml / min and the ventilation time is 5 min;

[0075] S3: sealing the open end of the quartz tube reactor by an oxyhydrogen flame generated by an oxyhydrogen flame sealing machine;

[0076] S4: placing the sealed quartz tube reactor into a heating furnace for heating at a temperature of 700°C and a reaction pressure of 23 MPa for heating times of 1 min, 5 min, 10 min, 30 min and 60 min respectively;

[0077] S5: after heating for 1 min, 5 min, 10 min, 30 min and 60 min, the quartz tube reactor is respectively removed from the heating furnace and cooled. At this time, there are solid residues, i.e., carbon microspheres, in the quartz tube reactor.

[0078] The solid residues in the quartz tube reactor were analyzed. The mass of carbon accounted for about 84%, 70%, 63%, 58% and 44% of the mass of carbon in the raw material, respectively. The electron microscope images are shown in the attached figure. Fig.10 The particle size distribution diagram is shown in the attached Fig.11 As shown, the gas phase product components (including C2H x , CO2, CH4, CO and H2), the particle size average, standard deviation, coefficient of variation and carbon conversion rate of carbon microspheres are shown in the following table:

[0079]

[0080] Embodiment 6

[0081] A method for preparing carbon microspheres by supercritical water resource degradation of waste plastics, comprising the following steps:

[0082] S1: 5.69 mg of cleaned and dried high-impact polystyrene and 108.17 μl of ultrapure water with a resistivity greater than 18.25 MΩ.cm were weighed by a precision balance and loaded into a quartz tube reactor.

[0083] 4.55 mg of washed and dried high-impact polystyrene and

[0084] 86.39 μl of ultrapure water with a resistivity greater than 18.25 MΩ.cm was placed in a quartz tube reactor and weighed.

[0085] 3.88 mg of washed and dried high-impact polystyrene and

[0086] 73.78 μl of ultrapure water with a resistivity greater than 18.25 MΩ.cm was placed in a quartz tube reactor, and 3.42 mg of cleaned and dried high-impact polystyrene and

[0087] 65.06 μl of ultrapure water with a resistivity greater than 18.25 MΩ.cm was loaded into the quartz tube reactor;

[0088] S2: introducing argon gas into the quartz tube reactor and exhausting the air in the quartz tube reactor to make the quartz tube reactor oxygen-free, wherein the ventilation rate of argon gas is 100 ml / min and the ventilation time is 5 min;

[0089] S3: sealing the open end of the quartz tube reactor by an oxyhydrogen flame generated by an oxyhydrogen flame sealing machine;

[0090] S4: placing the sealed quartz tube reactor into a heating furnace for heating at temperatures of 500°C, 600°C, 700°C and 800°C, respectively, with a reaction pressure of 23 MPa and a heating time of 10 min;

[0091] S5: The heated quartz tube reactors are removed from the heating furnace and cooled. At this time, there are solid residues, namely carbon microspheres, in the quartz tube reactors.

[0092] The solid residues in the quartz tube reactor were analyzed and the mass of carbon accounted for about 89%, 80%, 63% and 40% of the mass of carbon in the raw material, respectively. The electron microscope images are shown in the attached Fig.12 The particle size distribution diagram is shown in the attached Fig.13 As shown, the gas phase product components (including C2H x , CO2, CH4, CO and H2), the particle size average, standard deviation, coefficient of variation and carbon conversion rate of carbon microspheres are shown in the following table:

[0093]

[0094] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing carbon microspheres by supercritical water degradation of waste plastics, characterized in that: The following steps are involved: S1: Weigh the plastic sample and ultrapure water using a precision balance and load them into a quartz tube reactor; S2: introducing argon gas into the quartz tube reactor to exhaust the air in the quartz tube reactor so that there is no oxygen in the quartz tube reactor; S3: sealing the open end of the quartz tube reactor by an oxyhydrogen flame generated by an oxyhydrogen flame sealing machine; S4: placing the sealed quartz tube reactor into a heating furnace for heating; S5: The heated quartz tube reactor is removed from the heating furnace and cooled. At this time, there are solid residues, namely carbon microspheres, in the quartz tube reactor.

2. The method for preparing carbon microspheres by supercritical water degradation of waste plastics according to claim 1, characterized in that: In the step S1, the plastic sample includes polystyrene, acrylonitrile-butadiene-styrene terpolymer, polycarbonate and polypropylene.

3. The method for preparing carbon microspheres by supercritical water degradation of waste plastics according to claim 1, characterized in that: In step S1, the plastic sample needs to be cleaned and dried before being loaded into the quartz tube reactor.

4. The method for preparing carbon microspheres by supercritical water degradation of waste plastics according to claim 1, characterized in that: In the step S1, the resistivity of the ultrapure water is greater than 18.25 MΩ.cm.

5. The method for preparing carbon microspheres by supercritical water degradation of waste plastics according to claim 1, characterized in that: In step S2, the ventilation rate of argon gas is 100 ml / min, and the ventilation time is 5 min.

Images